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Acceptable shutter speeds

  1. What is an acceptable degree of error in a shutter before it needs to be CLA'd? +/- 10%? 15%? I am looking at my lenses with a homemade electronic tester and some are quite off. I have come to expect that in the faster speeds, especially in my old Universal and Synchro shutters, but what about the main speeds, say 1/2 to 1/60. How much drift is tolerable?
  2. I b'lieve, could be mistaken, that the standard limits are +/- 30%. This is a little more than half a stop off.
  3. There is no rule as long as the drift is consistent across the speed range.
  4. Unless the speeds are way off (Dan's 30 percent seems reasonable except for the top one or two speeds which are seldom even close) or something is malfunctioning, such as "T" or "B" not working, or the cocking lever isn't returning, etc., I wouldn't worry about it until the speeds change noticeably at 30 degrees F vs. 100 degrees F. If you shoot in a colder climate then more frequent servicing may be necessary due to lubricant degradation affecting speeds more the colder it gets.
  5. Flutots camera repair shows 20% for speeds 1/100 and slower, 30% for speeds 1/125 and faster. http://www.flutotscamerarepair.com/Shutterspeed.htm
    The Compur repair manual says 15% for speeds 1/100 and slower and 20% for speeds 1/125 and faster.
    This chart http://www.photographyuncapped.com/articles/photography/iso-shutter-speeds-f-stops/ helps show where your measured speeds fall.

    From repair experience shutters that were run until the stopped rarely come back to in tolerance on 50% of the speeds; 1 second to 1/50 in tolerance, faster 1 to 2 stops slow.
    Shutters run until they were 1 to 2 stops slow barely reach in tolerance on 70% of the speeds, 1 second to 1/125 in tolerance, faster 1/2 to 1 1/12 stops slow.
    Shutters serviced between 1/2 stop slow to 1 stop slow usually reach 90% in tolerance, 1 second to 1/200-1/250 in tolerance, faster 1/3 to 1 stop slow.
  6. If 1/2 sec is what it says, then 1 second is considered "acceptable". Same w/ 1/60. 1/30 would be OK. It's not often that the speeds actually run faster than what the shutter reads. If that happens, something is possibly jammed or broke.

    None of this matters except that 1/30 is tough going for hand holding sometimes. When I say that none of this matters, as long as you know what the speeds actually are you can get correct exposures. The only other time it might matter is if, for example, my Rolleicord 1/300 setting is an actual 1/150, which I can just about guarantee it is w/o testing it, then motion blur is an issue.
  7. I'd go with Carol Flutot's numbers. For some reason they ring a bell in the vacuum that has become my skull.
    I'm pretty sure they're ANSI standard.

    Wonder if ISO tolerance is the same?
  8. But what is the problem in LF-photography with a shutter with known deviations?
  9. If you are not interested in wear and tear use an Avery label.
    If you need to shoot on cold days you need lube in good condition.
  10. I've seen you post this before, it's rather interesting: Is your conclusion therefore that shutters should be regularly serviced regardless of whether they are showing signs of inaccuracy?

    Does regularity of usage change this? By which I mean, a 30-year-old shutter that has been used a hundred times a year vs the same shutter used 1000 times (or 10000 times) a year ... or a shutter that hasn't been used at all for 10 years ...
  11. My experience is UK repairers work to tighter tolerances than many in the US who give you a sheet of the actual speeds compared to the marked speeds.

    In addition many of my old Compurs some pre-WWI are more accurate than modern Copals, Compounds are similar. Lower build quality Betax, Alphax, Illex shutters seem the worst although easy to service.

  12. There are a couple of things to consider here.

    First, even a well-working and recently-serviced shutter is not going to be completely accurate to the marked shutter speeds. Clockwork shutters are notoriously slow at higher speeds. Most of us don't use them that much, but every shutter I have with a 1/500 sec. marking actually has a speed of about twice as long at that setting (i.e., 1/250 sec.).

    Shutters just need to be consistent to be useful. Springs weaken, there is friction in places in older shutters due to wear, etc., etc. that came make actual shutter speeds different than the marked ones. All we really need to know is what is actually happening to expose correctly.

    Every one of my shutters gets tested yearly and gets a sticker with the actual speeds (I list them in marked shutter speeds plus or minus exposure in thirds of a stop - e.g., I have a WF Ektar where the 1/2 sec. setting gives me 1/3 stop more exposure; I label this as 1/2+). When I send my shutters off to Carol Flutot's for CLA, I ask her to do the same. She always sends a nice list of shutter speeds in 1000s of a second which I convert to my system. One-third stop accuracy is good enough for me.

    If a shutter is inconsistent or seems to speed up/slow down depending on temperature, or if the clockwork seems to run irregularly, then a CLA is indicated. However, if everything runs smoothly and the speeds are not as marked but still consistent, simply work with them as they are.


  13. This would be a rarity. It is more common of 2 or 3 speed to be on and others off. Best to test and label each speed,or print the speeds on a card to be carried with the shutter.
  14. I support and practice PRO standards. PRO standards for camera shutters is the speeds should be within 1/3 stop of the indicated speed and should be serviced once the speeds are 1/2 stop either side of the target speed. The tolerances in my previous post when calculated for any given speed will be roughly 1/3 stop either side of the target speed. A thorough CLA will last at least 5 years on a frequently used shutter and 10+ years on infrequently used shutters. All speeds from 1 second to 1/125 are based on the main cocking spring tension and the delay timing, speeds above 1/125 are achieved with a booster spring.

    Its your equipment, treat it as you want.
  15. I've been a camera technician for 30 years and have repaired many shutters.

    I could tell many stories about camera shutters (and for that matter lenses and the affect they have on exposure - most people think it's the shutter causing their problem, when often it's the fact that not all lenses are calibrated the same. I had one photographer who used to come in every 6 months and we would re-calibrate all the lenses in his bag - 8 or 9 lenses to be within +/- 0.1 stop at f8. He said he could see the difference. Then there were the other working professional photographers who never bothered to have a lens re-calibrated because their photos came out fine...).

    The simple answer is a shutter needs to be consistent. Whether i'ts running at 1 sec or 1.2 seconds, or 1/60th or 1/45th is not really a issue, as long as it does it the same every time. As a rough guide I'd say a 25% variance is not going to cause a noticeable difference in your results, and you will probably not notice a 40% variation if you are shooting negative film.

    What most people forget is that unless you are doing machine processing of your negatives/slides variations in film processing will have as large an effect on your results as shutter timing will.....

    As shutterfinger said above - "its your equipment, treat it as you want"..